A method for preparing carbon fiber reinforced zirconium carbide ceramics

Abstract

The invention provides a preparation method of carbon fiber reinforced zirconium carbide ceramics, belonging to the technical field of ceramics; the preparation method comprises zirconium carbide pretreatment, preparation of vinylized carbon fiber, preparation of zirconium carbide carbon fiber, zirconium carbide carbon fiber modification, mixing and sintering steps; the zirconium carbide carbon fiber modification step comprises: adding zirconium carbide carbon fiber into N, N-dimethylformamide, stirring evenly, adding amino carbon fiber and sodium ethoxide, stirring reaction, reaction temperature is 32-36 DEG C, reaction time is 10-14h, after stirring, filtering and washing, freeze drying, after drying, naturally recovering to room temperature, and preparing modified zirconium carbide carbon fiber; the ceramic product prepared by the method of the invention has high yield rate, good mechanical property and excellent corrosion resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of ceramics, and in particular relates to a method for preparing carbon fiber reinforced zirconium carbide ceramics. Background Art

[0002] Zirconium carbide is a black solid with the advantages of high melting point, high hardness, high electrical conductivity and excellent chemical stability. As an extremely important new engineering ceramic raw material, it has high research value in the ceramic field.

[0003] However, zirconium carbide has poor toughness and is prone to through-cracks, causing irreversible losses. By adding fibers to make up for the lack of toughness, excellent ceramic materials can be obtained. Carbon fiber, as a new type of fiber material, has the advantages of high strength, high modulus, low density, and ultra-high temperature resistance, and can meet the use requirements in high-temperature aerobic environments. When carbon fiber is used as a reinforcing phase in zirconium carbide-based ceramics, the carbon fiber can form bridges between cracks, prevent crack expansion, and improve the toughness of the material.

[0004] However, the carbon fibers and zirconium carbide ceramic matrix cannot be well and evenly dispersed. The carbon fibers are unevenly dispersed and arranged in a disorderly manner, and the interface bonding with zirconium carbide is poor, which will affect the overall mechanical properties of the ceramic and even reduce the toughness.

[0005] In this regard, the prior art discloses the following:

[0006] CN110451969A discloses a carbon fiber-zirconium carbide composite material and a preparation method thereof, wherein zirconium carbide powder is mixed with a dispersant and deionized water to prepare a zirconium carbide slurry, and then the zirconium carbide slurry is coated on the carbon fiber to densify it, and after drying, the carbon fiber coated with the zirconium carbide slurry is immersed in a zirconium carbide precursor sol, and after drying, sintered to obtain a composite material;

[0007] The composite material produced by this patent has a bending strength of 270MPa and a fracture toughness of 16MPa·m 1 / 2 However, its bending strength is poor and its corrosion resistance is poor. In a more complex corrosion environment, the bending strength and fracture toughness drop sharply, which affects the application of ceramic materials.

[0008] CN112374906A discloses a method for preparing a carbon fiber toughened silicon carbide-zirconium carbide composite material, the preparation method comprising providing a carbon fiber preform, forming a porous carbon / carbon composite material containing pores inside the carbon fiber preform, preparing a carbon / silicon carbide-zirconium carbide ceramic matrix composite material by a reaction melt infiltration method, and finally preparing a carbon fiber toughened silicon carbide-zirconium carbide ceramic matrix composite material by an impregnation pyrolysis method;

[0009] This patent uses carbon fiber as the reinforcement phase and silicon carbide-zirconium carbide as the ceramic matrix. It combines the reaction infiltration method with the impregnation cracking method. However, the ceramic material produced still has the problem of poor corrosion resistance.

[0010] It can be seen that the existing technology mostly adopts the impregnation pyrolysis process when preparing zirconium carbide matrix and carbon fiber as the reinforcement phase ceramics. The ceramic materials obtained have poor corrosion resistance, which limits the application in complex corrosive environments.

[0011] Therefore, providing a method for preparing carbon fiber reinforced zirconium carbide ceramics, the obtained ceramic material has high toughness, high yield, good mechanical properties, and excellent corrosion resistance is a technical problem that needs to be solved urgently in the prior art. Summary of the invention

[0012] In order to solve the technical problems existing in the prior art, the present invention provides a method for preparing carbon fiber reinforced zirconium carbide ceramics. The prepared ceramic material has high toughness, high yield, good mechanical properties and excellent corrosion resistance.

[0013] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0014] A method for preparing carbon fiber reinforced zirconium carbide ceramics, including zirconium carbide pretreatment, preparation of vinylized carbon fiber, preparation of zirconium carbide-carbon fiber, zirconium carbide-carbon fiber modification, mixing and sintering steps, the specific operations are as follows:

[0015] 1. Zirconium carbide pretreatment

[0016] The zirconium carbide is placed in a nitric acid solution, the temperature is increased to 78-82°C, and the solution is stirred for 1.8-2.3 hours. After the heat preservation treatment is completed, the solution is filtered out and washed, and then placed in dimethyl sulfoxide. After stirring evenly, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide are added. The solution is stirred evenly, L-cysteine ​​is added, the pH is adjusted to 4.9-5.1, and the solution is stirred at 25-28°C in the dark for 5.8-6.2 hours. After the stirring reaction is completed, the solution is filtered out and washed, and then dried at 108-112°C for 9.8-10.4 hours to obtain pretreated zirconium carbide.

[0017] The particle size of the zirconium carbide is 310-330nm;

[0018] The mass volume ratio of the zirconium carbide, nitric acid solution, dimethyl sulfoxide, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide, and L-cysteine ​​is 4.2-4.7 g: 48-52 g: 240-260 mL: 10.6-11.0 g: 6.5-6.8 g: 5.7-6.0 g;

[0019] The mass concentration of the nitric acid solution is 23-26%.

[0020] 2. Preparation of Vinylated Carbon Fibers

[0021] Tetrahydrofuran is introduced into a reaction container, and carbon fiber is added. After stirring evenly, triethanolamine is added, and the temperature is raised to 30-34° C., and the reaction is stirred for 1.4-1.6 hours. After the stirring is completed, the carbon fiber is filtered out, washed, and then immersed in a vinyl reagent. The immersion temperature is 68-72° C., the heating rate is 4.8-5.2° C. / min, and the immersion time is 7.8-8.3 hours. After the immersion is completed, the carbon fiber is filtered and washed, and dried at 68-72° C. for 9.8-10.4 hours to obtain vinylized carbon fiber;

[0022] The vinyl reagent is composed of 23-27wt% ethanol solution, methacryloxypropyl trimethoxysilane, hexamethylene diisocyanate and fatty acid polyoxyethylene ester, and the mass ratio of the 23-27wt% ethanol solution, methacryloxypropyl trimethoxysilane, hexamethylene diisocyanate and fatty acid polyoxyethylene ester is 107-114:0.9-1.1:1.3-1.5:1.1-1.5;

[0023] The carbon fiber has a length of 8-12 μm and an aspect ratio of 16-18;

[0024] The volume mass ratio of the tetrahydrofuran, carbon fiber, triethanolamine and vinyl reagent is 95-110 mL: 9.7-10.3 g: 0.40-0.45 g: 112-116 g.

[0025] 3. Preparation of zirconium carbide-carbon fibers

[0026] Add pretreated zirconium carbide and vinylized carbon fiber to N, N-dimethylformamide, and after uniform dispersion, add benzoin n-butyl ether, stir evenly, and then perform ultraviolet-ultrasonic treatment, the ultrasonic power is 132-145W, the ultrasonic frequency is 27-33kHz, the ultraviolet wavelength is 360-370nm, the treatment time is 28-32min, after the treatment, filter and wash, and then vacuum dry, the drying time is 18-22h, and the drying temperature is 113-118°C to obtain zirconium carbide-carbon fiber;

[0027] The volume mass ratio of the N,N-dimethylformamide, pretreated zirconium carbide, vinylized carbon fiber and benzoin n-butyl ether is 490-510 mL: 4.0-4.4 g: 12.5-13.0 g: 0.36-0.40 g.

[0028] 4. Zirconium carbide-carbon fiber modification

[0029] The zirconium carbide-carbon fiber is put into N, N-dimethylformamide, stirred evenly, and then the amino carbon fiber and sodium ethoxide are added to react with stirring. The reaction temperature is 32-36°C, the reaction time is 10-14h, and the stirring speed is 262-275rpm. After the stirring is completed, it is filtered and washed, first freeze-dried at -27 to -23°C for 7.8-8.2h, and then freeze-dried at -40 to -35°C for 5.8-6.2h. After drying, it is naturally restored to room temperature to obtain modified zirconium carbide-carbon fiber;

[0030] The mass volume ratio of the zirconium carbide-carbon fiber, N,N-dimethylformamide, amino carbon fiber, and sodium ethoxide is 6.1-6.5 g:190-210 mL:2.0-2.2 g:0.6-0.8 g;

[0031] The preparation method of the amino carbon fiber is as follows: putting the carbon fiber into an ethanol solution, adding glycerol, stirring evenly, dropping ammonia water, and then adding polyethyleneimine, raising the temperature to 43-47° C., stirring and reacting for 0.8-1.2 hours, filtering, washing, and drying after the reaction is completed to obtain the amino carbon fiber;

[0032] The carbon fiber has a length of 8-12 μm and an aspect ratio of 16-18;

[0033] The mass volume ratio of the carbon fiber, ethanol solution, glycerol, ammonia water, and polyethyleneimine is 8.3-8.7 g: 88-92 g: 0.8-1.2 g: 3.3-3.7 mL: 1.2-1.4 g;

[0034] The mass concentration of the ethanol solution is 28-32%;

[0035] The mass concentration of the ammonia water is 28-32%.

[0036] 5. Mixing

[0037] Anhydrous ethanol is mixed with zirconium carbide and modified zirconium carbide-carbon fiber, and then zirconium oxide, polyvinyl alcohol and sodium carboxymethyl cellulose are added, and homogenization is performed. The homogenization pressure is 2.8-3.2 MPa, the homogenization time is 3.5-4.5 minutes, the homogenization number is 2 times, and after the homogenization is completed, drying is performed to obtain a mixed powder;

[0038] The mass ratio of anhydrous ethanol, zirconium carbide, modified zirconium carbide-carbon fiber, zirconium oxide, polyvinyl alcohol, and sodium carboxymethyl cellulose is 78-82:7.3-7.7:3.6-4.0:1.2-1.4:0.6-0.8:0.5-0.8;

[0039] The particle size of the zirconium carbide is 210-240nm;

[0040] The particle size of the zirconium oxide is 280-300 nm.

[0041] 6. Sintering

[0042] The mixed powder is added into a mold and sintered in an argon atmosphere at a sintering temperature of 1800-1820°C, a sintering time of 60-65min, and a sintering pressure of 30-34MPa. After sintering, the temperature is naturally lowered to room temperature to obtain a zirconium carbide ceramic product.

[0043] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0044] 1. The present invention uses zirconium carbide as a ceramic matrix and carbon fiber as a reinforcing phase to prepare a ceramic product, pre-treats the zirconium carbide, introduces a mercapto group on the surface of the zirconium carbide, vinylizes the carbon fiber, and then connects the zirconium carbide and the carbon fiber through a mercapto-ene click chemical reaction, thereby improving the compatibility and bonding of the carbon fiber and the zirconium carbide, and then uses amino carbon fiber to coat and modify the zirconium carbide-carbon fiber again, so that the amino group of the amino carbon fiber and the vinyl of the zirconium carbide-carbon fiber undergo Michael addition reaction, and the isocyanate group of the vinyl carbon fiber can be combined with the pre-treated zirconium carbide and the amino carbon fiber, thereby finally achieving the carbon fiber to carbon bonding. The two layers of zirconium carbide are coated with each other, forming a stable cross-linked structure, which fully and effectively realizes the reinforcing performance of carbon fiber for zirconium carbide matrix. During the sintering process, carbon fiber forms bridges between cracks to prevent the expansion of cracks, and can disperse the concentrated stress of the ceramic matrix, making the stress distribution more uniform, reducing the generation of cracks, improving the yield rate, and increasing toughness. The modified zirconium carbide-carbon fiber has good dispersibility with other components, and the obtained mixed powder has good homogeneity. The ceramic product obtained after sintering effectively reduces the generation of cracks, has good toughness, good mechanical properties, and excellent stability, and has been widely used in corrosive environments;

[0045] 2. The ceramic products prepared by the method of the present invention have a low crack rate and a finished product rate of 96-99%;

[0046] 3. The ceramic product prepared by the method of the present invention has a hardness of 26.8-27.3Gpa, a bending strength of 358-364MPa, and a fracture toughness of 6.3-6.7MPa·m 1 / 2 , elastic modulus is 391-398Gpa;

[0047] 4. The ceramic product prepared by the method of the present invention was heated to 1600°C at a rate of 20°C / min, and allowed to stand at 1600°C for 12 hours. After the standing period, the temperature was naturally lowered to room temperature, and then immersed in a 25wt% sodium hydroxide solution of 3 times the mass for 120 hours. After the immersion period, the ceramic product was filtered out and washed, and then dried at 110°C for 10 hours. After the drying period, the flexural strength was measured again to be 345-355MPa, and the fracture toughness was 6.0-6.4MPa·m 1 / 2 , the elastic modulus is 373-384Gpa. DETAILED DESCRIPTION

[0048] In order to more clearly understand the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described.

[0049] Example 1

[0050] 1. Zirconium carbide pretreatment

[0051] 4.5 g of zirconium carbide was placed in 50 g of 25 wt% nitric acid solution, the temperature was raised to 80°C, and the solution was stirred for 2.0 h. After the heat preservation treatment was completed, the solution was filtered out and washed, and then put into 250 mL of dimethyl sulfoxide. After stirring, 10.8 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 6.7 g of N-hydroxysuccinimide were added. The solution was stirred evenly, and 5.8 g of L-cysteine ​​was added. The pH was adjusted to 5.0, and the solution was stirred at 26°C in the dark for 6.0 h. After the stirring reaction was completed, the solution was filtered and washed, and dried at 110°C for 10 h to obtain pretreated zirconium carbide.

[0052] The particle size of the zirconium carbide is 320 nm.

[0053] 2. Preparation of Vinylated Carbon Fibers

[0054] 100 mL of tetrahydrofuran was introduced into the reaction container, 10.0 g of carbon fiber was added, and after stirring, 0.43 g of triethanolamine was added, the temperature was raised to 32° C., and the reaction was stirred for 1.5 h. After the stirring was completed, the carbon fiber was filtered out, washed, and then immersed in 114 g of vinyl reagent. The immersion temperature was 70° C., the heating rate was 5.0° C. / min, and the immersion time was 8.0 h. After the immersion was completed, it was filtered, washed, and dried at 70° C. for 10 h to obtain vinylized carbon fiber;

[0055] The vinyl reagent is composed of 25wt% ethanol solution, methacryloxypropyl trimethoxysilane, hexamethylene diisocyanate and fatty acid polyoxyethylene ester, and the mass ratio of the 25wt% ethanol solution, methacryloxypropyl trimethoxysilane, hexamethylene diisocyanate and fatty acid polyoxyethylene ester is 110:1.0:1.4:1.3;

[0056] The length of the carbon fiber is 10 μm, and the aspect ratio is 17.

[0057] 3. Preparation of zirconium carbide-carbon fibers

[0058] To 500 mL of N, N-dimethylformamide, 4.2 g of pretreated zirconium carbide and 12.7 g of vinylized carbon fiber were added. After uniform dispersion, 0.38 g of benzoin n-butyl ether was added. After stirring, ultraviolet-ultrasonic treatment was performed. The ultrasonic power was 140 W, the ultrasonic frequency was 30 kHz, the ultraviolet wavelength was 365 nm, and the treatment time was 30 min. After the treatment, it was filtered and washed and then vacuum dried for 20 h at a drying temperature of 115 ° C to obtain zirconium carbide-carbon fiber.

[0059] 4. Zirconium carbide-carbon fiber modification

[0060] 6.3 g zirconium carbide-carbon fiber was added to 200 mL N, N-dimethylformamide, and after being stirred evenly, 2.1 g amino carbon fiber and 0.7 g sodium ethoxide were added, and the reaction was stirred at 34°C, the reaction time was 12 h, and the stirring speed was 270 rpm. After the stirring was completed, it was filtered and washed, and then freeze-dried at -25°C for 8.0 h, and then freeze-dried at -37°C for 6.0 h. After drying, it was naturally restored to room temperature to obtain modified zirconium carbide-carbon fiber;

[0061] The preparation method of the amino carbon fiber is as follows: 8.5g of carbon fiber is added to 90g of 30wt% ethanol solution, 1.0g of propylene glycol is added, and after stirring evenly, 3.5mL of 30wt% ammonia water is added dropwise, and then 1.3g of polyethyleneimine is added, the temperature is increased to 45°C, and the reaction is stirred for 1.0h. After the reaction is completed, the mixture is filtered, washed, and dried to obtain the amino carbon fiber;

[0062] The length of the carbon fiber is 10 μm, and the aspect ratio is 17.

[0063] 5. Mixing

[0064] 80 g of anhydrous ethanol was mixed with 7.5 g of zirconium carbide and 3.8 g of modified zirconium carbide-carbon fiber, and then 1.3 g of zirconium oxide, 0.7 g of polyvinyl alcohol and 0.7 g of sodium carboxymethyl cellulose were added, and homogenization was performed at a homogenization pressure of 3.0 MPa, a homogenization time of 4.0 min, and a homogenization number of 2 times. After the homogenization, the mixed powder was dried to obtain a mixed powder;

[0065] The particle size of the zirconium carbide is 220 nm;

[0066] The particle size of the zirconium oxide is 290 nm.

[0067] 6. Sintering

[0068] The mixed powder is added into a mold and sintered in an argon atmosphere at a sintering temperature of 1810°C, a sintering time of 63 minutes, and a sintering pressure of 32 MPa. After sintering, the temperature is naturally lowered to room temperature to obtain a zirconium carbide ceramic product.

[0069] Example 2

[0070] 1. Zirconium carbide pretreatment

[0071] 4.2 g of zirconium carbide was placed in 48 g of 23 wt% nitric acid solution, the temperature was raised to 78°C, and the solution was stirred for 1.8 h. After the heat preservation treatment was completed, the solution was filtered out and washed, and then put into 240 mL of dimethyl sulfoxide. After stirring, 10.6 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 6.5 g of N-hydroxysuccinimide were added. The solution was stirred evenly, and 5.7 g of L-cysteine ​​was added. The pH was adjusted to 4.9, and the solution was stirred at 25°C in the dark for 5.8 h. After the stirring reaction was completed, the solution was filtered and washed, and dried at 108°C for 10.4 h to obtain pretreated zirconium carbide.

[0072] The particle size of the zirconium carbide is 310 nm.

[0073] 2. Preparation of Vinylated Carbon Fibers

[0074] 95 mL of tetrahydrofuran was introduced into the reaction container, 9.7 g of carbon fiber was added, and after stirring evenly, 0.40 g of triethanolamine was added, the temperature was raised to 30° C., and the reaction was stirred for 1.4 h. After the stirring was completed, the carbon fiber was filtered out, washed, and then placed in 112 g of vinyl reagent for impregnation. The impregnation temperature was 68° C., the heating rate was 4.8° C. / min, and the impregnation time was 7.8 h. After the impregnation was completed, it was filtered and washed, and dried at 68° C. for 10.4 h to obtain vinylized carbon fiber;

[0075] The vinyl reagent is composed of 23wt% ethanol solution, methacryloxypropyl trimethoxysilane, hexamethylene diisocyanate and fatty acid polyoxyethylene ester, and the mass ratio of the 23wt% ethanol solution, methacryloxypropyl trimethoxysilane, hexamethylene diisocyanate and fatty acid polyoxyethylene ester is 107:0.9:1.3:1.1;

[0076] The carbon fiber has a length of 8 μm and an aspect ratio of 16.

[0077] 3. Preparation of zirconium carbide-carbon fibers

[0078] To 490 mL of N, N-dimethylformamide, 4.0 g of pretreated zirconium carbide and 12.5 g of vinylized carbon fiber were added. After uniform dispersion, 0.36 g of benzoin n-butyl ether was added. After stirring, ultraviolet-ultrasonic treatment was performed. The ultrasonic power was 132 W, the ultrasonic frequency was 27 kHz, the ultraviolet wavelength was 360 nm, and the treatment time was 32 min. After the treatment, it was filtered and washed and then vacuum dried for 18 h at a drying temperature of 113 ° C to obtain zirconium carbide-carbon fiber.

[0079] 4. Zirconium carbide-carbon fiber modification

[0080] 6.1 g zirconium carbide-carbon fiber was added to 190 mL N, N-dimethylformamide, and after being stirred evenly, 2.0 g amino carbon fiber and 0.6 g sodium ethoxide were added, and the reaction was stirred at 32 ° C, the reaction time was 10 h, and the stirring speed was 262 rpm. After the stirring was completed, it was filtered and washed, first freeze-dried at -27 ° C for 7.8 h, and then freeze-dried at -40 ° C for 5.8 h. After drying, it was naturally restored to room temperature to obtain modified zirconium carbide-carbon fiber;

[0081] The preparation method of the amino carbon fiber is as follows: 8.3g of carbon fiber is added to 88g of 28wt% ethanol solution, 0.8g of propylene glycol is added, and after stirring evenly, 3.3mL of 28wt% ammonia water is added dropwise, and then 1.2g of polyethyleneimine is added, the temperature is increased to 43°C, and the reaction is stirred for 0.8h. After the reaction is completed, the mixture is filtered, washed, and dried to obtain the amino carbon fiber;

[0082] The carbon fiber has a length of 8 μm and an aspect ratio of 16.

[0083] 5. Mixing

[0084] 78 g of anhydrous ethanol was mixed with 7.3 g of zirconium carbide and 3.6 g of modified zirconium carbide-carbon fiber, and then 1.2 g of zirconium oxide, 0.6 g of polyvinyl alcohol and 0.5 g of sodium carboxymethyl cellulose were added, and homogenization was performed at a homogenization pressure of 2.8 MPa, a homogenization time of 3.5 min, and a homogenization number of 2 times. After the homogenization, the mixed powder was dried to obtain a mixed powder;

[0085] The particle size of the zirconium carbide is 210 nm;

[0086] The particle size of the zirconium oxide is 280 nm.

[0087] 6. Sintering

[0088] The mixed powder is added into a mold and sintered in an argon atmosphere at a sintering temperature of 1800°C, a sintering time of 65 minutes, and a sintering pressure of 34 MPa. After sintering, the temperature is naturally lowered to room temperature to obtain a zirconium carbide ceramic product.

[0089] Example 3

[0090] 1. Zirconium carbide pretreatment

[0091] 4.7 g of zirconium carbide was placed in 52 g of 26 wt% nitric acid solution, the temperature was raised to 82°C, and the solution was stirred for 2.3 h. After the heat preservation treatment was completed, the solution was filtered out and washed, and then put into 260 mL of dimethyl sulfoxide. After stirring, 11.0 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 6.8 g of N-hydroxysuccinimide were added. The solution was stirred evenly, 6.0 g of L-cysteine ​​was added, the pH was adjusted to 5.1, and the solution was stirred at 28°C in the dark for 6.2 h. After the stirring reaction was completed, the solution was filtered and washed, and dried at 112°C for 9.8 h to obtain pretreated zirconium carbide.

[0092] The particle size of the zirconium carbide is 330 nm.

[0093] 2. Preparation of Vinylated Carbon Fibers

[0094] 110 mL of tetrahydrofuran was introduced into the reaction container, 10.3 g of carbon fiber was added, and after stirring, 0.45 g of triethanolamine was added, the temperature was raised to 34 ° C, and the reaction was stirred for 1.6 hours. After the stirring was completed, the carbon fiber was filtered out, washed, and placed in 116 g of vinyl reagent for impregnation. The impregnation temperature was 72 ° C, the heating rate was 5.2 ° C / min, and the impregnation time was 8.3 hours. After the impregnation was completed, it was filtered and washed, and dried at 72 ° C for 9.8 hours to obtain vinylized carbon fiber;

[0095] The vinyl reagent is composed of 27wt% ethanol solution, methacryloxypropyl trimethoxysilane, hexamethylene diisocyanate and fatty acid polyoxyethylene ester, and the mass ratio of the 27wt% ethanol solution, methacryloxypropyl trimethoxysilane, hexamethylene diisocyanate and fatty acid polyoxyethylene ester is 114:1.1:1.5:1.5;

[0096] The carbon fiber has a length of 12 μm and an aspect ratio of 18.

[0097] 3. Preparation of zirconium carbide-carbon fibers

[0098] To 510 mL of N, N-dimethylformamide, 4.4 g of pretreated zirconium carbide and 13.0 g of vinylized carbon fiber were added. After uniform dispersion, 0.40 g of benzoin n-butyl ether was added. After stirring, ultraviolet-ultrasonic treatment was performed. The ultrasonic power was 145 W, the ultrasonic frequency was 33 kHz, the ultraviolet wavelength was 370 nm, and the treatment time was 28 min. After the treatment, it was filtered and washed and then vacuum dried for 22 h at a drying temperature of 118 ° C to obtain zirconium carbide-carbon fiber.

[0099] 4. Zirconium carbide-carbon fiber modification

[0100] 6.5 g zirconium carbide-carbon fiber was added to 210 mL N, N-dimethylformamide, and after stirring, 2.2 g amino carbon fiber and 0.8 g sodium ethoxide were added for stirring reaction. The reaction temperature was 36 ° C, the reaction time was 14 h, and the stirring speed was 275 rpm. After the stirring was completed, it was filtered and washed, first freeze-dried at -23 ° C for 8.2 h, and then freeze-dried at -35 ° C for 6.2 h. After drying, it was naturally restored to room temperature to obtain modified zirconium carbide-carbon fiber;

[0101] The preparation method of the amino carbon fiber is as follows: 8.7g of carbon fiber is added to 92g of 32wt% ethanol solution, 1.2g of propylene glycol is added, and after stirring evenly, 3.7mL of 32wt% ammonia water is added dropwise, and then 1.4g of polyethyleneimine is added, the temperature is raised to 47°C, and the reaction is stirred for 1.2h. After the reaction is completed, the mixture is filtered, washed, and dried to obtain the amino carbon fiber;

[0102] The carbon fiber has a length of 12 μm and an aspect ratio of 18.

[0103] 5. Mixing

[0104] 82g of anhydrous ethanol was mixed with 7.7g of zirconium carbide and 4.0g of modified zirconium carbide-carbon fiber, and then 1.4g of zirconium oxide, 0.8g of polyvinyl alcohol and 0.8g of sodium carboxymethyl cellulose were added, and homogenization was performed at a homogenization pressure of 3.2MPa, a homogenization time of 4.5min, and a homogenization number of 2 times. After the homogenization, the mixed powder was dried to obtain a mixed powder;

[0105] The particle size of the zirconium carbide is 240 nm;

[0106] The particle size of the zirconium oxide is 300 nm.

[0107] 6. Sintering

[0108] The mixed powder is added into a mold and sintered in an argon atmosphere at a sintering temperature of 1820°C, a sintering time of 60 minutes, and a sintering pressure of 30 MPa. After sintering, the temperature is naturally lowered to room temperature to obtain a zirconium carbide ceramic product.

[0109] Comparative Example 1

[0110] Based on Example 1, the changes are as follows:

[0111] The preparation method of the pretreated zirconium carbide is as follows: 4.5 g of zirconium carbide is placed in 50 g of 25 wt% nitric acid solution, the temperature is raised to 80° C., the solution is kept warm and stirred for 2.0 h, after the heat preservation treatment is completed, the solution is filtered out and washed, and dried at 110° C. for 10 h to obtain the pretreated zirconium carbide; the particle size of the zirconium carbide is 320 nm;

[0112] The preparation method of the vinylized carbon fiber is as follows: 100 mL of tetrahydrofuran is introduced into a reaction container, 10.0 g of carbon fiber is added, and after being stirred evenly, 0.43 g of triethanolamine is added, the temperature is raised to 32° C., and the reaction is stirred for 1.5 hours. After the stirring is completed, the carbon fiber is filtered out, washed, and dried at 70° C. for 10 hours to obtain the vinylized carbon fiber;

[0113] The rest of the operations are the same.

[0114] Comparative Example 2

[0115] Based on Example 1, the changes are as follows: the zirconium carbide-carbon fiber modification step is omitted; in the mixing step, the modified zirconium carbide-carbon fiber is replaced with zirconium carbide-carbon fiber in equal amounts;

[0116] The rest of the operations are the same.

[0117] Performance Testing

[0118] 1. Crack rate

[0119] The yield rates of ceramic products prepared by the methods of Examples 1-3 and Comparative Examples 1-2 were statistically analyzed, and the results are as follows:

[0120]

[0121] 2. Comprehensive mechanical properties

[0122] Ceramic products were prepared by the methods of Examples 1-3 and Comparative Examples 1-2, respectively, and the mechanical properties were tested. The results are as follows:

[0123]

[0124] 3. Corrosion resistance

[0125] The ceramic products obtained in Examples 1-3 and Comparative Examples 1-2 were heated to 1600°C at a rate of 20°C / min, and allowed to stand at 1600°C for 12 hours. After the standing period, the temperature was naturally lowered to room temperature, and then immersed in a 25wt% sodium hydroxide solution of 3 times the mass for 120 hours. After the immersion period, the solution was filtered out and washed, and then dried at 110°C for 10 hours. After the drying period, the samples to be tested were obtained. The flexural strength, fracture toughness and elastic modulus of the samples to be tested were tested, and the test results were as follows:

[0126]

[0127] The invention uses zirconium carbide as a ceramic matrix and carbon fiber as a reinforcing phase to prepare a ceramic product, pre-treats the zirconium carbide, introduces a mercapto group on the surface of the zirconium carbide, performs vinyl treatment on the carbon fiber, and then connects the zirconium carbide and the carbon fiber through a mercapto-ene click chemical reaction, thereby improving the compatibility and bonding of the carbon fiber and the zirconium carbide, and then uses amino carbon fiber to coat and modify the zirconium carbide-carbon fiber again, so that the amino group of the amino carbon fiber and the vinyl of the zirconium carbide-carbon fiber undergo Michael addition reaction, and the isocyanate group of the vinyl carbon fiber can be combined with the pre-treated zirconium carbide and the amino carbon fiber, thereby finally achieving the carbon fiber to carbonization. The two layers of zirconium coating form a stable cross-linked structure with each other, fully and effectively realizing the reinforcing performance of carbon fiber for zirconium carbide matrix. During the sintering process, carbon fiber forms bridges between cracks to prevent crack expansion and disperse the concentrated stress of the ceramic matrix, making the stress distribution more uniform, reducing the generation of cracks, improving the yield rate, and increasing toughness. The modified zirconium carbide-carbon fiber has good dispersion with other components, and the obtained mixed powder has good homogeneity. The ceramic product obtained after sintering effectively reduces the generation of cracks, has good toughness, good mechanical properties, and excellent stability, and has been widely used in corrosive environments.

[0128] Comparative Example 1 is to treat zirconium carbide in a nitric acid solution and treat carbon fiber with triethanolamine. In the zirconium carbide-carbon fiber step, carbon fiber and zirconium carbide cannot be evenly and firmly bonded, and thiol-ene click chemical reaction cannot be carried out between them. The bonding force between the two is poor and the dispersion is uneven. When modifying zirconium carbide-carbon fiber, the amino carbon fiber does not react fully with it, and the obtained modified zirconium carbide-carbon fiber has poor stability, and the reinforcing performance of carbon fiber for zirconium carbide matrix cannot be fully exerted, and the generation of cracks cannot be effectively avoided, and the comprehensive performance of ceramic products such as mechanical properties and corrosion resistance is affected, shortening the service life of ceramic products;

[0129] Comparative Example 2 omits the modification step of zirconium carbide-carbon fiber, and directly uses zirconium carbide-carbon fiber to prepare the mixture, which only achieves a layer of coating of carbon fiber on zirconium carbide, weakening the reinforcing performance of carbon fiber on the zirconium carbide matrix, thereby reducing the comprehensive performance of Comparative Example 2 and limiting the scope of use.

[0130] Unless otherwise specified, all percentages used in the present invention are by mass.

[0131] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing carbon fiber reinforced zirconium carbide ceramics, characterized in that: The method comprises the steps of pre-treating zirconium carbide, preparing vinylized carbon fiber, preparing zirconium carbide-carbon fiber, modifying zirconium carbide-carbon fiber, mixing and sintering; The zirconium carbide pretreatment step comprises placing the zirconium carbide in a nitric acid solution, raising the temperature to 78-82° C., keeping the temperature and stirring for 1.8-2.3 hours, filtering out and washing after the heat preservation treatment, and then putting it into dimethyl sulfoxide, stirring evenly, adding 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide, continuing to stir evenly, adding L-cysteine, adjusting the pH to 4.9-5.1, stirring and reacting at 25-28° C. in the dark for 5.8-6.2 hours, filtering and washing after the stirring reaction, and drying at 108-112° C. for 9.8-10.4 hours to obtain the pretreated zirconium carbide; The steps of preparing vinylized carbon fiber are as follows: introducing tetrahydrofuran into a reaction container, adding carbon fiber, stirring evenly, adding triethanolamine, raising the temperature to 30-34° C., stirring for reaction for 1.4-1.6 hours, filtering out the carbon fiber after stirring, washing it, and then placing it in a vinyl reagent for impregnation, the impregnation temperature is 68-72° C., the heating rate is 4.8-5.2° C. / min, the impregnation time is 7.8-8.3 hours, after the impregnation is completed, filtering and washing, and drying at 68-72° C. for 9.8-10.4 hours to obtain the vinylized carbon fiber; The vinyl reagent is composed of 23-27wt% ethanol solution, methacryloxypropyltrimethoxysilane, hexamethylene diisocyanate and fatty acid polyoxyethylene ester; The step of preparing zirconium carbide-carbon fiber is as follows: adding pretreated zirconium carbide and vinylized carbon fiber to N,N-dimethylformamide, after uniform dispersion, adding benzoin n-butyl ether, stirring evenly, and then performing ultraviolet-ultrasonic treatment, the ultrasonic power is 132-145W, the ultrasonic frequency is 27-33kHz, the ultraviolet wavelength is 360-370nm, the treatment time is 28-32min, after the treatment is completed, filtering and washing, vacuum drying is performed, the drying time is 18-22h, and the drying temperature is 113-118°C, so as to obtain zirconium carbide-carbon fiber; The zirconium carbide-carbon fiber modification step is to put the zirconium carbide-carbon fiber into N,N-dimethylformamide, stir evenly, add amino carbon fiber and sodium ethoxide, and stir to react, the reaction temperature is 32-36°C, the reaction time is 10-14h, the stirring speed is 262-275rpm, after the stirring is completed, filter and wash, and then freeze-dry. After drying, it is naturally restored to room temperature to obtain modified zirconium carbide-carbon fiber.

2. The method for preparing a carbon fiber reinforced zirconium carbide ceramic according to claim 1, characterized in that: In the zirconium carbide pretreatment step, the particle size of the zirconium carbide is 310-330 nm; The mass volume ratio of the zirconium carbide, nitric acid solution, dimethyl sulfoxide, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide, and L-cysteine ​​is 4.2-4.7 g: 48-52 g: 240-260 mL: 10.6-11.0 g: 6.5-6.8 g: 5.7-6.0 g; The mass concentration of the nitric acid solution is 23-26%.

3. The method for preparing a carbon fiber reinforced zirconium carbide ceramic according to claim 1, characterized in that: In the step of preparing vinylized carbon fiber, the length of the carbon fiber is 8-12 μm, and the aspect ratio is 16-18; The volume mass ratio of the tetrahydrofuran, carbon fiber, triethanolamine and vinyl reagent is 95-110 mL: 9.7-10.3 g: 0.40-0.45 g: 112-116 g; In the vinyl reagent, the mass ratio of the 23-27wt% ethanol solution, methacryloxypropyltrimethoxysilane, hexamethylene diisocyanate and fatty acid polyoxyethylene ester is 107-114:0.9-1.1:1.3-1.5:1.1-1.

5.

4. The method for preparing a carbon fiber reinforced zirconium carbide ceramic according to claim 1, characterized in that: In the step of preparing zirconium carbide-carbon fiber, the volume mass ratio of the N,N-dimethylformamide, pretreated zirconium carbide, vinylized carbon fiber, and benzoin n-butyl ether is 490-510 mL: 4.0-4.4 g: 12.5-13.0 g: 0.36-0.40 g.

5. The method for preparing a carbon fiber reinforced zirconium carbide ceramic according to claim 1, characterized in that: In the zirconium carbide-carbon fiber modification step, the mass volume ratio of the zirconium carbide-carbon fiber, N,N-dimethylformamide, amino carbon fiber, and sodium ethoxide is 6.1-6.5 g:190-210 mL:2.0-2.2 g:0.6-0.8 g; The freeze drying is first performed at -27 to -23°C for 7.8 to 8.2 hours, and then at -40 to -35°C for 5.8 to 6.2 hours.

6. The method for preparing a carbon fiber reinforced zirconium carbide ceramic according to claim 1, characterized in that: The preparation method of the amino carbon fiber is as follows: putting the carbon fiber into an ethanol solution, adding glycerol, stirring evenly, dropping ammonia water, and then adding polyethyleneimine, raising the temperature to 43-47° C., stirring and reacting for 0.8-1.2 hours, filtering, washing, and drying after the reaction is completed to obtain the amino carbon fiber; The carbon fiber has a length of 8-12 μm and an aspect ratio of 16-18; The mass volume ratio of the carbon fiber, ethanol solution, glycerol, ammonia water, and polyethyleneimine is 8.3-8.7 g: 88-92 g: 0.8-1.2 g: 3.3-3.7 mL: 1.2-1.4 g; The mass concentration of the ethanol solution is 28-32%; The mass concentration of the ammonia water is 28-32%.

7. The method for preparing carbon fiber reinforced zirconium carbide ceramics according to claim 1, characterized in that: The mixing step comprises mixing anhydrous ethanol with zirconium carbide and modified zirconium carbide-carbon fiber, then adding zirconium oxide, polyvinyl alcohol and sodium carboxymethyl cellulose, and performing homogenization, the homogenization pressure is 2.8-3.2 MPa, the homogenization time is 3.5-4.5 min, the homogenization times are 2 times, and after the homogenization is completed, drying is performed to obtain a mixed powder; The mass ratio of anhydrous ethanol, zirconium carbide, modified zirconium carbide-carbon fiber, zirconium oxide, polyvinyl alcohol, and sodium carboxymethyl cellulose is 78-82:7.3-7.7:3.6-4.0:1.2-1.4:0.6-0.8:0.5-0.8; The particle size of the zirconium carbide is 210-240nm; The particle size of the zirconium oxide is 280-300 nm.

8. The method for preparing carbon fiber reinforced zirconium carbide ceramics according to claim 1, characterized in that: The sintering step is to add the mixed powder into a mold and sinter it in an argon atmosphere at a sintering temperature of 1800-1820° C., a sintering time of 60-65 min, and a sintering pressure of 30-34 MPa. After the sintering is completed, the temperature is naturally lowered to room temperature to obtain a zirconium carbide ceramic product.

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